arch/s390/kernel/smp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  SMP related functions
   4  *
   5  *    Copyright IBM Corp. 1999, 2012
   6  *    Author(s): Denis Joseph Barrow,
   7  *               Martin Schwidefsky <schwidefsky@de.ibm.com>,
   8  *               Heiko Carstens <heiko.carstens@de.ibm.com>,
   9  *
  10  *  based on other smp stuff by
  11  *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
  12  *    (c) 1998 Ingo Molnar
  13  *
  14  * The code outside of smp.c uses logical cpu numbers, only smp.c does
  15  * the translation of logical to physical cpu ids. All new code that
  16  * operates on physical cpu numbers needs to go into smp.c.
  17  */
  18
  19 #define KMSG_COMPONENT "cpu"
  20 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  21
  22 #include <linux/workqueue.h>
  23 #include <linux/bootmem.h>
  24 #include <linux/export.h>
  25 #include <linux/init.h>
  26 #include <linux/mm.h>
  27 #include <linux/err.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/kernel_stat.h>
  30 #include <linux/delay.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/irqflags.h>
  33 #include <linux/cpu.h>
  34 #include <linux/slab.h>
  35 #include <linux/sched/hotplug.h>
  36 #include <linux/sched/task_stack.h>
  37 #include <linux/crash_dump.h>
  38 #include <linux/memblock.h>
  39 #include <linux/kprobes.h>
  40 #include <asm/asm-offsets.h>
  41 #include <asm/diag.h>
  42 #include <asm/switch_to.h>
  43 #include <asm/facility.h>
  44 #include <asm/ipl.h>
  45 #include <asm/setup.h>
  46 #include <asm/irq.h>
  47 #include <asm/tlbflush.h>
  48 #include <asm/vtimer.h>
  49 #include <asm/lowcore.h>
  50 #include <asm/sclp.h>
  51 #include <asm/vdso.h>
  52 #include <asm/debug.h>
  53 #include <asm/os_info.h>
  54 #include <asm/sigp.h>
  55 #include <asm/idle.h>
  56 #include <asm/nmi.h>
  57 #include <asm/topology.h>
  58 #include "entry.h"
  59
  60 enum {
  61         ec_schedule = 0,
  62         ec_call_function_single,
  63         ec_stop_cpu,
  64 };
  65
  66 enum {
  67         CPU_STATE_STANDBY,
  68         CPU_STATE_CONFIGURED,
  69 };
  70
  71 static DEFINE_PER_CPU(struct cpu *, cpu_device);
  72
  73 struct pcpu {
  74         struct lowcore *lowcore;        /* lowcore page(s) for the cpu */
  75         unsigned long ec_mask;          /* bit mask for ec_xxx functions */
  76         unsigned long ec_clk;           /* sigp timestamp for ec_xxx */
  77         signed char state;              /* physical cpu state */
  78         signed char polarization;       /* physical polarization */
  79         u16 address;                    /* physical cpu address */
  80 };
  81
  82 static u8 boot_core_type;
  83 static struct pcpu pcpu_devices[NR_CPUS];
  84
  85 unsigned int smp_cpu_mt_shift;
  86 EXPORT_SYMBOL(smp_cpu_mt_shift);
  87
  88 unsigned int smp_cpu_mtid;
  89 EXPORT_SYMBOL(smp_cpu_mtid);
  90
  91 #ifdef CONFIG_CRASH_DUMP
  92 __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
  93 #endif
  94
  95 static unsigned int smp_max_threads __initdata = -1U;
  96
  97 static int __init early_nosmt(char *s)
  98 {
  99         smp_max_threads = 1;
 100         return 0;
 101 }
 102 early_param("nosmt", early_nosmt);
 103
 104 static int __init early_smt(char *s)
 105 {
 106         get_option(&s, &smp_max_threads);
 107         return 0;
 108 }
 109 early_param("smt", early_smt);
 110
 111 /*
 112  * The smp_cpu_state_mutex must be held when changing the state or polarization
 113  * member of a pcpu data structure within the pcpu_devices arreay.
 114  */
 115 DEFINE_MUTEX(smp_cpu_state_mutex);
 116
 117 /*
 118  * Signal processor helper functions.
 119  */
 120 static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm)
 121 {
 122         int cc;
 123
 124         while (1) {
 125                 cc = __pcpu_sigp(addr, order, parm, NULL);
 126                 if (cc != SIGP_CC_BUSY)
 127                         return cc;
 128                 cpu_relax();
 129         }
 130 }
 131
 132 static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
 133 {
 134         int cc, retry;
 135
 136         for (retry = 0; ; retry++) {
 137                 cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
 138                 if (cc != SIGP_CC_BUSY)
 139                         break;
 140                 if (retry >= 3)
 141                         udelay(10);
 142         }
 143         return cc;
 144 }
 145
 146 static inline int pcpu_stopped(struct pcpu *pcpu)
 147 {
 148         u32 uninitialized_var(status);
 149
 150         if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
 151                         0, &status) != SIGP_CC_STATUS_STORED)
 152                 return 0;
 153         return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
 154 }
 155
 156 static inline int pcpu_running(struct pcpu *pcpu)
 157 {
 158         if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
 159                         0, NULL) != SIGP_CC_STATUS_STORED)
 160                 return 1;
 161         /* Status stored condition code is equivalent to cpu not running. */
 162         return 0;
 163 }
 164
 165 /*
 166  * Find struct pcpu by cpu address.
 167  */
 168 static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
 169 {
 170         int cpu;
 171
 172         for_each_cpu(cpu, mask)
 173                 if (pcpu_devices[cpu].address == address)
 174                         return pcpu_devices + cpu;
 175         return NULL;
 176 }
 177
 178 static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
 179 {
 180         int order;
 181
 182         if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
 183                 return;
 184         order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
 185         pcpu->ec_clk = get_tod_clock_fast();
 186         pcpu_sigp_retry(pcpu, order, 0);
 187 }
 188
 189 #define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 190 #define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 191
 192 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 193 {
 194         unsigned long async_stack, panic_stack;
 195         struct lowcore *lc;
 196
 197         if (pcpu != &pcpu_devices[0]) {
 198                 pcpu->lowcore = (struct lowcore *)
 199                         __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
 200                 async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
 201                 panic_stack = __get_free_page(GFP_KERNEL);
 202                 if (!pcpu->lowcore || !panic_stack || !async_stack)
 203                         goto out;
 204         } else {
 205                 async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET;
 206                 panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET;
 207         }
 208         lc = pcpu->lowcore;
 209         memcpy(lc, &S390_lowcore, 512);
 210         memset((char *) lc + 512, 0, sizeof(*lc) - 512);
 211         lc->async_stack = async_stack + ASYNC_FRAME_OFFSET;
 212         lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET;
 213         lc->cpu_nr = cpu;
 214         lc->spinlock_lockval = arch_spin_lockval(cpu);
 215         lc->spinlock_index = 0;
 216         lc->br_r1_trampoline = 0x07f1;  /* br %r1 */
 217         if (nmi_alloc_per_cpu(lc))
 218                 goto out;
 219         if (vdso_alloc_per_cpu(lc))
 220                 goto out_mcesa;
 221         lowcore_ptr[cpu] = lc;
 222         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 223         return 0;
 224
 225 out_mcesa:
 226         nmi_free_per_cpu(lc);
 227 out:
 228         if (pcpu != &pcpu_devices[0]) {
 229                 free_page(panic_stack);
 230                 free_pages(async_stack, ASYNC_ORDER);
 231                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 232         }
 233         return -ENOMEM;
 234 }
 235
 236 #ifdef CONFIG_HOTPLUG_CPU
 237
 238 static void pcpu_free_lowcore(struct pcpu *pcpu)
 239 {
 240         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 241         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 242         vdso_free_per_cpu(pcpu->lowcore);
 243         nmi_free_per_cpu(pcpu->lowcore);
 244         if (pcpu == &pcpu_devices[0])
 245                 return;
 246         free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET);
 247         free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER);
 248         free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 249 }
 250
 251 #endif /* CONFIG_HOTPLUG_CPU */
 252
 253 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 254 {
 255         struct lowcore *lc = pcpu->lowcore;
 256
 257         cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 258         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 259         lc->cpu_nr = cpu;
 260         lc->spinlock_lockval = arch_spin_lockval(cpu);
 261         lc->spinlock_index = 0;
 262         lc->percpu_offset = __per_cpu_offset[cpu];
 263         lc->kernel_asce = S390_lowcore.kernel_asce;
 264         lc->user_asce = S390_lowcore.kernel_asce;
 265         lc->machine_flags = S390_lowcore.machine_flags;
 266         lc->user_timer = lc->system_timer = lc->steal_timer = 0;
 267         __ctl_store(lc->cregs_save_area, 0, 15);
 268         lc->cregs_save_area[1] = lc->kernel_asce;
 269         lc->cregs_save_area[7] = lc->vdso_asce;
 270         save_access_regs((unsigned int *) lc->access_regs_save_area);
 271         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 272                sizeof(lc->stfle_fac_list));
 273         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 274                sizeof(lc->alt_stfle_fac_list));
 275         arch_spin_lock_setup(cpu);
 276 }
 277
 278 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 279 {
 280         struct lowcore *lc = pcpu->lowcore;
 281
 282         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 283                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 284         lc->current_task = (unsigned long) tsk;
 285         lc->lpp = LPP_MAGIC;
 286         lc->current_pid = tsk->pid;
 287         lc->user_timer = tsk->thread.user_timer;
 288         lc->guest_timer = tsk->thread.guest_timer;
 289         lc->system_timer = tsk->thread.system_timer;
 290         lc->hardirq_timer = tsk->thread.hardirq_timer;
 291         lc->softirq_timer = tsk->thread.softirq_timer;
 292         lc->steal_timer = 0;
 293 }
 294
 295 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 296 {
 297         struct lowcore *lc = pcpu->lowcore;
 298
 299         lc->restart_stack = lc->kernel_stack;
 300         lc->restart_fn = (unsigned long) func;
 301         lc->restart_data = (unsigned long) data;
 302         lc->restart_source = -1UL;
 303         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 304 }
 305
 306 /*
 307  * Call function via PSW restart on pcpu and stop the current cpu.
 308  */
 309 static void pcpu_delegate(struct pcpu *pcpu, void (*func)(void *),
 310                           void *data, unsigned long stack)
 311 {
 312         struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
 313         unsigned long source_cpu = stap();
 314
 315         __load_psw_mask(PSW_KERNEL_BITS);
 316         if (pcpu->address == source_cpu)
 317                 func(data);     /* should not return */
 318         /* Stop target cpu (if func returns this stops the current cpu). */
 319         pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 320         /* Restart func on the target cpu and stop the current cpu. */
 321         mem_assign_absolute(lc->restart_stack, stack);
 322         mem_assign_absolute(lc->restart_fn, (unsigned long) func);
 323         mem_assign_absolute(lc->restart_data, (unsigned long) data);
 324         mem_assign_absolute(lc->restart_source, source_cpu);
 325         __bpon();
 326         asm volatile(
 327                 "0:     sigp    0,%0,%2 # sigp restart to target cpu\n"
 328                 "       brc     2,0b    # busy, try again\n"
 329                 "1:     sigp    0,%1,%3 # sigp stop to current cpu\n"
 330                 "       brc     2,1b    # busy, try again\n"
 331                 : : "d" (pcpu->address), "d" (source_cpu),
 332                     "K" (SIGP_RESTART), "K" (SIGP_STOP)
 333                 : "0", "1", "cc");
 334         for (;;) ;
 335 }
 336
 337 /*
 338  * Enable additional logical cpus for multi-threading.
 339  */
 340 static int pcpu_set_smt(unsigned int mtid)
 341 {
 342         int cc;
 343
 344         if (smp_cpu_mtid == mtid)
 345                 return 0;
 346         cc = __pcpu_sigp(0, SIGP_SET_MULTI_THREADING, mtid, NULL);
 347         if (cc == 0) {
 348                 smp_cpu_mtid = mtid;
 349                 smp_cpu_mt_shift = 0;
 350                 while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
 351                         smp_cpu_mt_shift++;
 352                 pcpu_devices[0].address = stap();
 353         }
 354         return cc;
 355 }
 356
 357 /*
 358  * Call function on an online CPU.
 359  */
 360 void smp_call_online_cpu(void (*func)(void *), void *data)
 361 {
 362         struct pcpu *pcpu;
 363
 364         /* Use the current cpu if it is online. */
 365         pcpu = pcpu_find_address(cpu_online_mask, stap());
 366         if (!pcpu)
 367                 /* Use the first online cpu. */
 368                 pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
 369         pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
 370 }
 371
 372 /*
 373  * Call function on the ipl CPU.
 374  */
 375 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 376 {
 377         struct lowcore *lc = pcpu_devices->lowcore;
 378
 379         if (pcpu_devices[0].address == stap())
 380                 lc = &S390_lowcore;
 381
 382         pcpu_delegate(&pcpu_devices[0], func, data,
 383                       lc->panic_stack - PANIC_FRAME_OFFSET + PAGE_SIZE);
 384 }
 385
 386 int smp_find_processor_id(u16 address)
 387 {
 388         int cpu;
 389
 390         for_each_present_cpu(cpu)
 391                 if (pcpu_devices[cpu].address == address)
 392                         return cpu;
 393         return -1;
 394 }
 395
 396 bool notrace arch_vcpu_is_preempted(int cpu)
 397 {
 398         if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
 399                 return false;
 400         if (pcpu_running(pcpu_devices + cpu))
 401                 return false;
 402         return true;
 403 }
 404 EXPORT_SYMBOL(arch_vcpu_is_preempted);
 405
 406 void notrace smp_yield_cpu(int cpu)
 407 {
 408         if (MACHINE_HAS_DIAG9C) {
 409                 diag_stat_inc_norecursion(DIAG_STAT_X09C);
 410                 asm volatile("diag %0,0,0x9c"
 411                              : : "d" (pcpu_devices[cpu].address));
 412         } else if (MACHINE_HAS_DIAG44) {
 413                 diag_stat_inc_norecursion(DIAG_STAT_X044);
 414                 asm volatile("diag 0,0,0x44");
 415         }
 416 }
 417
 418 /*
 419  * Send cpus emergency shutdown signal. This gives the cpus the
 420  * opportunity to complete outstanding interrupts.
 421  */
 422 void notrace smp_emergency_stop(void)
 423 {
 424         cpumask_t cpumask;
 425         u64 end;
 426         int cpu;
 427
 428         cpumask_copy(&cpumask, cpu_online_mask);
 429         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 430
 431         end = get_tod_clock() + (1000000UL << 12);
 432         for_each_cpu(cpu, &cpumask) {
 433                 struct pcpu *pcpu = pcpu_devices + cpu;
 434                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 435                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 436                                    0, NULL) == SIGP_CC_BUSY &&
 437                        get_tod_clock() < end)
 438                         cpu_relax();
 439         }
 440         while (get_tod_clock() < end) {
 441                 for_each_cpu(cpu, &cpumask)
 442                         if (pcpu_stopped(pcpu_devices + cpu))
 443                                 cpumask_clear_cpu(cpu, &cpumask);
 444                 if (cpumask_empty(&cpumask))
 445                         break;
 446                 cpu_relax();
 447         }
 448 }
 449 NOKPROBE_SYMBOL(smp_emergency_stop);
 450
 451 /*
 452  * Stop all cpus but the current one.
 453  */
 454 void smp_send_stop(void)
 455 {
 456         int cpu;
 457
 458         /* Disable all interrupts/machine checks */
 459         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 460         trace_hardirqs_off();
 461
 462         debug_set_critical();
 463
 464         if (oops_in_progress)
 465                 smp_emergency_stop();
 466
 467         /* stop all processors */
 468         for_each_online_cpu(cpu) {
 469                 if (cpu == smp_processor_id())
 470                         continue;
 471                 pcpu_sigp_retry(pcpu_devices + cpu, SIGP_STOP, 0);
 472                 while (!pcpu_stopped(pcpu_devices + cpu))
 473                         cpu_relax();
 474         }
 475 }
 476
 477 /*
 478  * This is the main routine where commands issued by other
 479  * cpus are handled.
 480  */
 481 static void smp_handle_ext_call(void)
 482 {
 483         unsigned long bits;
 484
 485         /* handle bit signal external calls */
 486         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 487         if (test_bit(ec_stop_cpu, &bits))
 488                 smp_stop_cpu();
 489         if (test_bit(ec_schedule, &bits))
 490                 scheduler_ipi();
 491         if (test_bit(ec_call_function_single, &bits))
 492                 generic_smp_call_function_single_interrupt();
 493 }
 494
 495 static void do_ext_call_interrupt(struct ext_code ext_code,
 496                                   unsigned int param32, unsigned long param64)
 497 {
 498         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 499         smp_handle_ext_call();
 500 }
 501
 502 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 503 {
 504         int cpu;
 505
 506         for_each_cpu(cpu, mask)
 507                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 508 }
 509
 510 void arch_send_call_function_single_ipi(int cpu)
 511 {
 512         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 513 }
 514
 515 /*
 516  * this function sends a 'reschedule' IPI to another CPU.
 517  * it goes straight through and wastes no time serializing
 518  * anything. Worst case is that we lose a reschedule ...
 519  */
 520 void smp_send_reschedule(int cpu)
 521 {
 522         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 523 }
 524
 525 /*
 526  * parameter area for the set/clear control bit callbacks
 527  */
 528 struct ec_creg_mask_parms {
 529         unsigned long orval;
 530         unsigned long andval;
 531         int cr;
 532 };
 533
 534 /*
 535  * callback for setting/clearing control bits
 536  */
 537 static void smp_ctl_bit_callback(void *info)
 538 {
 539         struct ec_creg_mask_parms *pp = info;
 540         unsigned long cregs[16];
 541
 542         __ctl_store(cregs, 0, 15);
 543         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 544         __ctl_load(cregs, 0, 15);
 545 }
 546
 547 /*
 548  * Set a bit in a control register of all cpus
 549  */
 550 void smp_ctl_set_bit(int cr, int bit)
 551 {
 552         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 553
 554         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 555 }
 556 EXPORT_SYMBOL(smp_ctl_set_bit);
 557
 558 /*
 559  * Clear a bit in a control register of all cpus
 560  */
 561 void smp_ctl_clear_bit(int cr, int bit)
 562 {
 563         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 564
 565         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 566 }
 567 EXPORT_SYMBOL(smp_ctl_clear_bit);
 568
 569 #ifdef CONFIG_CRASH_DUMP
 570
 571 int smp_store_status(int cpu)
 572 {
 573         struct pcpu *pcpu = pcpu_devices + cpu;
 574         unsigned long pa;
 575
 576         pa = __pa(&pcpu->lowcore->floating_pt_save_area);
 577         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 578                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 579                 return -EIO;
 580         if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 581                 return 0;
 582         pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
 583         if (MACHINE_HAS_GS)
 584                 pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
 585         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 586                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 587                 return -EIO;
 588         return 0;
 589 }
 590
 591 /*
 592  * Collect CPU state of the previous, crashed system.
 593  * There are four cases:
 594  * 1) standard zfcp dump
 595  *    condition: OLDMEM_BASE == NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 596  *    The state for all CPUs except the boot CPU needs to be collected
 597  *    with sigp stop-and-store-status. The boot CPU state is located in
 598  *    the absolute lowcore of the memory stored in the HSA. The zcore code
 599  *    will copy the boot CPU state from the HSA.
 600  * 2) stand-alone kdump for SCSI (zfcp dump with swapped memory)
 601  *    condition: OLDMEM_BASE != NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 602  *    The state for all CPUs except the boot CPU needs to be collected
 603  *    with sigp stop-and-store-status. The firmware or the boot-loader
 604  *    stored the registers of the boot CPU in the absolute lowcore in the
 605  *    memory of the old system.
 606  * 3) kdump and the old kernel did not store the CPU state,
 607  *    or stand-alone kdump for DASD
 608  *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
 609  *    The state for all CPUs except the boot CPU needs to be collected
 610  *    with sigp stop-and-store-status. The kexec code or the boot-loader
 611  *    stored the registers of the boot CPU in the memory of the old system.
 612  * 4) kdump and the old kernel stored the CPU state
 613  *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
 614  *    This case does not exist for s390 anymore, setup_arch explicitly
 615  *    deactivates the elfcorehdr= kernel parameter
 616  */
 617 static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
 618                                      bool is_boot_cpu, unsigned long page)
 619 {
 620         __vector128 *vxrs = (__vector128 *) page;
 621
 622         if (is_boot_cpu)
 623                 vxrs = boot_cpu_vector_save_area;
 624         else
 625                 __pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
 626         save_area_add_vxrs(sa, vxrs);
 627 }
 628
 629 static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 630                                      bool is_boot_cpu, unsigned long page)
 631 {
 632         void *regs = (void *) page;
 633
 634         if (is_boot_cpu)
 635                 copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
 636         else
 637                 __pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
 638         save_area_add_regs(sa, regs);
 639 }
 640
 641 void __init smp_save_dump_cpus(void)
 642 {
 643         int addr, boot_cpu_addr, max_cpu_addr;
 644         struct save_area *sa;
 645         unsigned long page;
 646         bool is_boot_cpu;
 647
 648         if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
 649                 /* No previous system present, normal boot. */
 650                 return;
 651         /* Allocate a page as dumping area for the store status sigps */
 652         page = memblock_alloc_base(PAGE_SIZE, PAGE_SIZE, 1UL << 31);
 653         /* Set multi-threading state to the previous system. */
 654         pcpu_set_smt(sclp.mtid_prev);
 655         boot_cpu_addr = stap();
 656         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 657         for (addr = 0; addr <= max_cpu_addr; addr++) {
 658                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
 659                     SIGP_CC_NOT_OPERATIONAL)
 660                         continue;
 661                 is_boot_cpu = (addr == boot_cpu_addr);
 662                 /* Allocate save area */
 663                 sa = save_area_alloc(is_boot_cpu);
 664                 if (!sa)
 665                         panic("could not allocate memory for save area\n");
 666                 if (MACHINE_HAS_VX)
 667                         /* Get the vector registers */
 668                         smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
 669                 /*
 670                  * For a zfcp dump OLDMEM_BASE == NULL and the registers
 671                  * of the boot CPU are stored in the HSA. To retrieve
 672                  * these registers an SCLP request is required which is
 673                  * done by drivers/s390/char/zcore.c:init_cpu_info()
 674                  */
 675                 if (!is_boot_cpu || OLDMEM_BASE)
 676                         /* Get the CPU registers */
 677                         smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
 678         }
 679         memblock_free(page, PAGE_SIZE);
 680         diag308_reset();
 681         pcpu_set_smt(0);
 682 }
 683 #endif /* CONFIG_CRASH_DUMP */
 684
 685 void smp_cpu_set_polarization(int cpu, int val)
 686 {
 687         pcpu_devices[cpu].polarization = val;
 688 }
 689
 690 int smp_cpu_get_polarization(int cpu)
 691 {
 692         return pcpu_devices[cpu].polarization;
 693 }
 694
 695 static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
 696 {
 697         static int use_sigp_detection;
 698         int address;
 699
 700         if (use_sigp_detection || sclp_get_core_info(info, early)) {
 701                 use_sigp_detection = 1;
 702                 for (address = 0;
 703                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 704                      address += (1U << smp_cpu_mt_shift)) {
 705                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
 706                             SIGP_CC_NOT_OPERATIONAL)
 707                                 continue;
 708                         info->core[info->configured].core_id =
 709                                 address >> smp_cpu_mt_shift;
 710                         info->configured++;
 711                 }
 712                 info->combined = info->configured;
 713         }
 714 }
 715
 716 static int smp_add_present_cpu(int cpu);
 717
 718 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 719                         bool configured, bool early)
 720 {
 721         struct pcpu *pcpu;
 722         int cpu, nr, i;
 723         u16 address;
 724
 725         nr = 0;
 726         if (sclp.has_core_type && core->type != boot_core_type)
 727                 return nr;
 728         cpu = cpumask_first(avail);
 729         address = core->core_id << smp_cpu_mt_shift;
 730         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 731                 if (pcpu_find_address(cpu_present_mask, address + i))
 732                         continue;
 733                 pcpu = pcpu_devices + cpu;
 734                 pcpu->address = address + i;
 735                 if (configured)
 736                         pcpu->state = CPU_STATE_CONFIGURED;
 737                 else
 738                         pcpu->state = CPU_STATE_STANDBY;
 739                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 740                 set_cpu_present(cpu, true);
 741                 if (!early && smp_add_present_cpu(cpu) != 0)
 742                         set_cpu_present(cpu, false);
 743                 else
 744                         nr++;
 745                 cpumask_clear_cpu(cpu, avail);
 746                 cpu = cpumask_next(cpu, avail);
 747         }
 748         return nr;
 749 }
 750
 751 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 752 {
 753         struct sclp_core_entry *core;
 754         static cpumask_t avail;
 755         bool configured;
 756         u16 core_id;
 757         int nr, i;
 758
 759         nr = 0;
 760         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 761         /*
 762          * Add IPL core first (which got logical CPU number 0) to make sure
 763          * that all SMT threads get subsequent logical CPU numbers.
 764          */
 765         if (early) {
 766                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 767                 for (i = 0; i < info->configured; i++) {
 768                         core = &info->core[i];
 769                         if (core->core_id == core_id) {
 770                                 nr += smp_add_core(core, &avail, true, early);
 771                                 break;
 772                         }
 773                 }
 774         }
 775         for (i = 0; i < info->combined; i++) {
 776                 configured = i < info->configured;
 777                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 778         }
 779         return nr;
 780 }
 781
 782 void __init smp_detect_cpus(void)
 783 {
 784         unsigned int cpu, mtid, c_cpus, s_cpus;
 785         struct sclp_core_info *info;
 786         u16 address;
 787
 788         /* Get CPU information */
 789         info = memblock_virt_alloc(sizeof(*info), 8);
 790         smp_get_core_info(info, 1);
 791         /* Find boot CPU type */
 792         if (sclp.has_core_type) {
 793                 address = stap();
 794                 for (cpu = 0; cpu < info->combined; cpu++)
 795                         if (info->core[cpu].core_id == address) {
 796                                 /* The boot cpu dictates the cpu type. */
 797                                 boot_core_type = info->core[cpu].type;
 798                                 break;
 799                         }
 800                 if (cpu >= info->combined)
 801                         panic("Could not find boot CPU type");
 802         }
 803
 804         /* Set multi-threading state for the current system */
 805         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 806         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 807         pcpu_set_smt(mtid);
 808
 809         /* Print number of CPUs */
 810         c_cpus = s_cpus = 0;
 811         for (cpu = 0; cpu < info->combined; cpu++) {
 812                 if (sclp.has_core_type &&
 813                     info->core[cpu].type != boot_core_type)
 814                         continue;
 815                 if (cpu < info->configured)
 816                         c_cpus += smp_cpu_mtid + 1;
 817                 else
 818                         s_cpus += smp_cpu_mtid + 1;
 819         }
 820         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 821
 822         /* Add CPUs present at boot */
 823         get_online_cpus();
 824         __smp_rescan_cpus(info, true);
 825         put_online_cpus();
 826         memblock_free_early((unsigned long)info, sizeof(*info));
 827 }
 828
 829 /*
 830  *      Activate a secondary processor.
 831  */
 832 static void smp_start_secondary(void *cpuvoid)
 833 {
 834         int cpu = raw_smp_processor_id();
 835
 836         S390_lowcore.last_update_clock = get_tod_clock();
 837         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 838         S390_lowcore.restart_fn = (unsigned long) do_restart;
 839         S390_lowcore.restart_data = 0;
 840         S390_lowcore.restart_source = -1UL;
 841         restore_access_regs(S390_lowcore.access_regs_save_area);
 842         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 843         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 844         set_cpu_flag(CIF_ASCE_PRIMARY);
 845         set_cpu_flag(CIF_ASCE_SECONDARY);
 846         cpu_init();
 847         rcu_cpu_starting(cpu);
 848         preempt_disable();
 849         init_cpu_timer();
 850         vtime_init();
 851         pfault_init();
 852         notify_cpu_starting(cpu);
 853         if (topology_cpu_dedicated(cpu))
 854                 set_cpu_flag(CIF_DEDICATED_CPU);
 855         else
 856                 clear_cpu_flag(CIF_DEDICATED_CPU);
 857         set_cpu_online(cpu, true);
 858         inc_irq_stat(CPU_RST);
 859         local_irq_enable();
 860         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 861 }
 862
 863 /* Upping and downing of CPUs */
 864 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 865 {
 866         struct pcpu *pcpu = pcpu_devices + cpu;
 867         int rc;
 868
 869         if (pcpu->state != CPU_STATE_CONFIGURED)
 870                 return -EIO;
 871         if (pcpu_sigp_retry(pcpu, SIGP_INITIAL_CPU_RESET, 0) !=
 872             SIGP_CC_ORDER_CODE_ACCEPTED)
 873                 return -EIO;
 874
 875         rc = pcpu_alloc_lowcore(pcpu, cpu);
 876         if (rc)
 877                 return rc;
 878         pcpu_prepare_secondary(pcpu, cpu);
 879         pcpu_attach_task(pcpu, tidle);
 880         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 881         /* Wait until cpu puts itself in the online & active maps */
 882         while (!cpu_online(cpu))
 883                 cpu_relax();
 884         return 0;
 885 }
 886
 887 static unsigned int setup_possible_cpus __initdata;
 888
 889 static int __init _setup_possible_cpus(char *s)
 890 {
 891         get_option(&s, &setup_possible_cpus);
 892         return 0;
 893 }
 894 early_param("possible_cpus", _setup_possible_cpus);
 895
 896 #ifdef CONFIG_HOTPLUG_CPU
 897
 898 int __cpu_disable(void)
 899 {
 900         unsigned long cregs[16];
 901
 902         /* Handle possible pending IPIs */
 903         smp_handle_ext_call();
 904         set_cpu_online(smp_processor_id(), false);
 905         /* Disable pseudo page faults on this cpu. */
 906         pfault_fini();
 907         /* Disable interrupt sources via control register. */
 908         __ctl_store(cregs, 0, 15);
 909         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 910         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 911         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 912         __ctl_load(cregs, 0, 15);
 913         clear_cpu_flag(CIF_NOHZ_DELAY);
 914         return 0;
 915 }
 916
 917 void __cpu_die(unsigned int cpu)
 918 {
 919         struct pcpu *pcpu;
 920
 921         /* Wait until target cpu is down */
 922         pcpu = pcpu_devices + cpu;
 923         while (!pcpu_stopped(pcpu))
 924                 cpu_relax();
 925         pcpu_free_lowcore(pcpu);
 926         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 927         cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 928 }
 929
 930 void __noreturn cpu_die(void)
 931 {
 932         idle_task_exit();
 933         __bpon();
 934         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 935         for (;;) ;
 936 }
 937
 938 #endif /* CONFIG_HOTPLUG_CPU */
 939
 940 void __init smp_fill_possible_mask(void)
 941 {
 942         unsigned int possible, sclp_max, cpu;
 943
 944         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 945         sclp_max = min(smp_max_threads, sclp_max);
 946         sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
 947         possible = setup_possible_cpus ?: nr_cpu_ids;
 948         possible = min(possible, sclp_max);
 949         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 950                 set_cpu_possible(cpu, true);
 951 }
 952
 953 void __init smp_prepare_cpus(unsigned int max_cpus)
 954 {
 955         /* request the 0x1201 emergency signal external interrupt */
 956         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 957                 panic("Couldn't request external interrupt 0x1201");
 958         /* request the 0x1202 external call external interrupt */
 959         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 960                 panic("Couldn't request external interrupt 0x1202");
 961 }
 962
 963 void __init smp_prepare_boot_cpu(void)
 964 {
 965         struct pcpu *pcpu = pcpu_devices;
 966
 967         WARN_ON(!cpu_present(0) || !cpu_online(0));
 968         pcpu->state = CPU_STATE_CONFIGURED;
 969         pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
 970         S390_lowcore.percpu_offset = __per_cpu_offset[0];
 971         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 972 }
 973
 974 void __init smp_cpus_done(unsigned int max_cpus)
 975 {
 976 }
 977
 978 void __init smp_setup_processor_id(void)
 979 {
 980         pcpu_devices[0].address = stap();
 981         S390_lowcore.cpu_nr = 0;
 982         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
 983         S390_lowcore.spinlock_index = 0;
 984 }
 985
 986 /*
 987  * the frequency of the profiling timer can be changed
 988  * by writing a multiplier value into /proc/profile.
 989  *
 990  * usually you want to run this on all CPUs ;)
 991  */
 992 int setup_profiling_timer(unsigned int multiplier)
 993 {
 994         return 0;
 995 }
 996
 997 #ifdef CONFIG_HOTPLUG_CPU
 998 static ssize_t cpu_configure_show(struct device *dev,
 999                                   struct device_attribute *attr, char *buf)
1000 {
1001         ssize_t count;
1002
1003         mutex_lock(&smp_cpu_state_mutex);
1004         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1005         mutex_unlock(&smp_cpu_state_mutex);
1006         return count;
1007 }
1008
1009 static ssize_t cpu_configure_store(struct device *dev,
1010                                    struct device_attribute *attr,
1011                                    const char *buf, size_t count)
1012 {
1013         struct pcpu *pcpu;
1014         int cpu, val, rc, i;
1015         char delim;
1016
1017         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1018                 return -EINVAL;
1019         if (val != 0 && val != 1)
1020                 return -EINVAL;
1021         get_online_cpus();
1022         mutex_lock(&smp_cpu_state_mutex);
1023         rc = -EBUSY;
1024         /* disallow configuration changes of online cpus and cpu 0 */
1025         cpu = dev->id;
1026         cpu = smp_get_base_cpu(cpu);
1027         if (cpu == 0)
1028                 goto out;
1029         for (i = 0; i <= smp_cpu_mtid; i++)
1030                 if (cpu_online(cpu + i))
1031                         goto out;
1032         pcpu = pcpu_devices + cpu;
1033         rc = 0;
1034         switch (val) {
1035         case 0:
1036                 if (pcpu->state != CPU_STATE_CONFIGURED)
1037                         break;
1038                 rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
1039                 if (rc)
1040                         break;
1041                 for (i = 0; i <= smp_cpu_mtid; i++) {
1042                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1043                                 continue;
1044                         pcpu[i].state = CPU_STATE_STANDBY;
1045                         smp_cpu_set_polarization(cpu + i,
1046                                                  POLARIZATION_UNKNOWN);
1047                 }
1048                 topology_expect_change();
1049                 break;
1050         case 1:
1051                 if (pcpu->state != CPU_STATE_STANDBY)
1052                         break;
1053                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1054                 if (rc)
1055                         break;
1056                 for (i = 0; i <= smp_cpu_mtid; i++) {
1057                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1058                                 continue;
1059                         pcpu[i].state = CPU_STATE_CONFIGURED;
1060                         smp_cpu_set_polarization(cpu + i,
1061                                                  POLARIZATION_UNKNOWN);
1062                 }
1063                 topology_expect_change();
1064                 break;
1065         default:
1066                 break;
1067         }
1068 out:
1069         mutex_unlock(&smp_cpu_state_mutex);
1070         put_online_cpus();
1071         return rc ? rc : count;
1072 }
1073 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1074 #endif /* CONFIG_HOTPLUG_CPU */
1075
1076 static ssize_t show_cpu_address(struct device *dev,
1077                                 struct device_attribute *attr, char *buf)
1078 {
1079         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1080 }
1081 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1082
1083 static struct attribute *cpu_common_attrs[] = {
1084 #ifdef CONFIG_HOTPLUG_CPU
1085         &dev_attr_configure.attr,
1086 #endif
1087         &dev_attr_address.attr,
1088         NULL,
1089 };
1090
1091 static struct attribute_group cpu_common_attr_group = {
1092         .attrs = cpu_common_attrs,
1093 };
1094
1095 static struct attribute *cpu_online_attrs[] = {
1096         &dev_attr_idle_count.attr,
1097         &dev_attr_idle_time_us.attr,
1098         NULL,
1099 };
1100
1101 static struct attribute_group cpu_online_attr_group = {
1102         .attrs = cpu_online_attrs,
1103 };
1104
1105 static int smp_cpu_online(unsigned int cpu)
1106 {
1107         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1108
1109         return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1110 }
1111 static int smp_cpu_pre_down(unsigned int cpu)
1112 {
1113         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1114
1115         sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1116         return 0;
1117 }
1118
1119 static int smp_add_present_cpu(int cpu)
1120 {
1121         struct device *s;
1122         struct cpu *c;
1123         int rc;
1124
1125         c = kzalloc(sizeof(*c), GFP_KERNEL);
1126         if (!c)
1127                 return -ENOMEM;
1128         per_cpu(cpu_device, cpu) = c;
1129         s = &c->dev;
1130         c->hotpluggable = 1;
1131         rc = register_cpu(c, cpu);
1132         if (rc)
1133                 goto out;
1134         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1135         if (rc)
1136                 goto out_cpu;
1137         rc = topology_cpu_init(c);
1138         if (rc)
1139                 goto out_topology;
1140         return 0;
1141
1142 out_topology:
1143         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1144 out_cpu:
1145 #ifdef CONFIG_HOTPLUG_CPU
1146         unregister_cpu(c);
1147 #endif
1148 out:
1149         return rc;
1150 }
1151
1152 #ifdef CONFIG_HOTPLUG_CPU
1153
1154 int __ref smp_rescan_cpus(void)
1155 {
1156         struct sclp_core_info *info;
1157         int nr;
1158
1159         info = kzalloc(sizeof(*info), GFP_KERNEL);
1160         if (!info)
1161                 return -ENOMEM;
1162         smp_get_core_info(info, 0);
1163         get_online_cpus();
1164         mutex_lock(&smp_cpu_state_mutex);
1165         nr = __smp_rescan_cpus(info, false);
1166         mutex_unlock(&smp_cpu_state_mutex);
1167         put_online_cpus();
1168         kfree(info);
1169         if (nr)
1170                 topology_schedule_update();
1171         return 0;
1172 }
1173
1174 static ssize_t __ref rescan_store(struct device *dev,
1175                                   struct device_attribute *attr,
1176                                   const char *buf,
1177                                   size_t count)
1178 {
1179         int rc;
1180
1181         rc = lock_device_hotplug_sysfs();
1182         if (rc)
1183                 return rc;
1184         rc = smp_rescan_cpus();
1185         unlock_device_hotplug();
1186         return rc ? rc : count;
1187 }
1188 static DEVICE_ATTR_WO(rescan);
1189 #endif /* CONFIG_HOTPLUG_CPU */
1190
1191 static int __init s390_smp_init(void)
1192 {
1193         int cpu, rc = 0;
1194
1195 #ifdef CONFIG_HOTPLUG_CPU
1196         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1197         if (rc)
1198                 return rc;
1199 #endif
1200         for_each_present_cpu(cpu) {
1201                 rc = smp_add_present_cpu(cpu);
1202                 if (rc)
1203                         goto out;
1204         }
1205
1206         rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
1207                                smp_cpu_online, smp_cpu_pre_down);
1208         rc = rc <= 0 ? rc : 0;
1209 out:
1210         return rc;
1211 }
1212 subsys_initcall(s390_smp_init);